XF 1.1 W3C Markup Validation Service?

Since I'm a total noob to Xenforo, I've been looking at some web based tutorials located here:http://www.html.net/tutorials/
They cover the basic functions of HTML, CSS, PHP and JavaScript. I've picked up a few things so it's been worthwhile for me.

One topic discussed was web standards and validation. This location: http://validator.w3.org/ has a resource for you enter your forum index and receive a validation report. I tried it with the Xenforo forum I'm working on and received 9 errors. As a comparison I tried with my current phpBB forum and received 35 errors. Are validation services useful?